In situ optical 3D sensor for precise extrusion die measurement

In hot forging, the rejection of parts due to tool wear results in substantial economic and environmental costs. Conventional wear detection methods rely on disassembling the tool for inspection, limiting real-time analysis and predictive maintenance. This paper presents a novel, miniaturized in-situ optical 3D sensor designed for the direct measurement of extrusion die wear during operation. Based on structured light and a stereo-endoscopic configuration, the system addresses significant challenges such as limited installation space, high temperatures, and optically non-cooperative functional surfaces. The sensor comprises thermal and particulate shielding, pneumatic surface cleaning, and a compact rigid endoscope-based optical setup. A laboratory prototype demonstrates successful 3D reconstruction of fine surface features and minimal systematic deviation. Preliminary evaluations confirm the system’s potential for non-destructive, high-resolution in-situ measurement, supporting the long-term goal of enabling predictive tool maintenance in industrial forging environments.